Reinford building panel



Jan. 26, 1954 N. J. CAMPBELL REINFORCED BUILDING PANEL Filed Feb. 12, 1948 l l illllll 3 FIG. 7

J8 INVENTOR 'NEAL. J. CAMPBELL FIG.

ATTORNEY Patented Jan. 26, 1954 UNITED STATES PATENT OFFICE REINFORCED BUILDING PANEL Neal J. Campbell, St. Louis, Mo. Application February 12, 1948, Serial No. 7,845

6 Claims.

This invention relates to improvements in the construction of panel type buildings and panels therefor, and more particularly to an improved panel of low-cost, high-strength, light-weight type, and improved methods of forming and manufacturing such panels for use in a variety of building structures.

Numerous attempts have heretofore been made to design panel elements suitable for use in and as parts of the walls, roofs and like parts of residential and other buildings. However, so far as is known to this applicant, all such panels which have heretofore appeared in trade are subject to many shortcomings, among which may be noted insufdcient structural strength, particularly an inability to resist high bending and shear stresses; furthermore, most or all of the panels heretofore utilized in housing assembly are difficult and expensive to manufacture and insulate, and are not readily subject to adequate water proofing treatment. Accordingly, the present invention has as its major and general objective, the attainment of a panel for general building purposes which possesses the noted attributes.

A further and highly important objective realized in the present invention consists in a structural combination of initially separate spaced slabs of concrete or similar setting material through the use of metallically united structural web members intervening the slabs, so as to produce thereof a panel which is the equivalent of a truss, and in fact may be utilized in many situations calling for a truss-like structure.

A further object of the invention is attained in an improved multiple-slab building panel providing an internal space with inherent air insulation features, or suitable for the ready reception of insultation materials of fibrous or other types, and which provides by reason of its improved construction, only a minimum thermal path between the outside and inside of the panel thus minimizing heat transfer when the panel is utilized as an element of an outside building structurt.

More particularly stated in respect to the technique, steps, and method of producing panels of the noted type, there is objectively realized an economical, eflicient and low-cost production of slabs ready for final assembly as a single operation.

Another and highly important object of the invention is realized in an improved technique for utilization of prestressed concrete in parts of the slabs constituting individually or in as- 2 sembly, the building panels of the present invention.

The foregoing and numerous other objects will more clearly appear from the following detailed description of a presently preferred example embodying the present improvements, and of an advanced technique for their production, particularly when considered in connection with the accompanying drawing, in which:

Fig. 1 is a diagrammatic top or plan view of a mold or form suitable for casting a plurality of the slabs made in accordance with the present improvements, certain parts being omitted for clearness of illustration;

Fig. 2 is a side elevation of an assembly for tensioning certain of the reinforcing elements extending through the mold or form;

Fig. 3 is a fragmentary elevational view of a face of one of the vertical partitions utilized in the form, and showing a preferred arrangement of wire slots therein;

Fig. 4 is a plan or face view of one end portion of a two-slab panel, and in a form suitable for assembly in a Wall or other element of a build- Fig. 5 is a fragmentary edge view taken in the zone of a joint between two adiacent slabs in an erected wall, partition or the like;

Fig. 6 is a fragmentary sectional view, considerably enlarged, and being taken through a corner portion of a two-slab panel, particularly along line B6 of Fig. 4;

Fig. 7 is a view taken similarly to Fig. 6 but showing a modified form of a panel or sectional unit of double character;

Fig. 8 is a fragmentary face or plan view of a slightly modified form of concrete slab embodying present improvements, and as particularly,

adapted for use in a single thickness, and

Fig. 9 is a fragmentary sectional view as taken along line 9-9 of Fig. 8.

Proceeding first to describe a preferred form of the panel and elements thereof, it will be seen that the panel is comprised of a pair of spaced concrete slabs including an upper or outer such element generally indicated at 20, and an inner or lower such element designated at 2|. These slabs are or may be uniform, each being of relatively thin or shallow dimension, in proportion to its width and length, and usually for convenience, but without restrictions, of rectangular form. One example of a slab of suitable and preferred dimensions is to construct the panels in a width of 3 ft., and a length of approximately 9 ft., with a depth or thickness of 1%,

inches. As will later better appear, the improved method of making the panels enables a reduction, yet with requisite strength, of the thickness in proportion to area, hence results in obvious economies in cost and weight of materials and in shipping, handling and storage expense.

Since the two slab structures are or may be identical, a description of the structure of one, will suffice for both. Arranged lengthwise say of the slab ZO is a plurality of rod orwire elements, preferably wire of a high tensile strength and. of the order of /8 inch diameter. These wires are arranged in approximate parallelism from end to end of the slab, and with an evencenterrspacing,

say of 3 inches, with the outermost such wires located somewhat inwardly of the lateral'margins of the slab.

By further preference the wires are arranged in a plurality of depthwise spaced courses; alternate wires being near the outer surface and the intervening wiressomewhatnearer the inner surface of the slab, those of the two coursesbeing nevertheless mutually: parallel, and the two courses disposed substantially equidistanctly on opposite .sides'of amedianplane of the slab paralleltoiits face. By means. andsteps of the method hereinafter described, the wires; are substantially tensioned: and elongated, as by application of a high: stretching effect prior to pouring the slab, whereby, incident to'at least a partial release of wire tension in the course of setting, :th rconcreteiof the slab, due'to thetension of the wires, is maintained:under a-degree of endwise compression.

The internal reinforcing structure of the slab includes as a further preference-when the panel is used in external wall construction, a plurality "of cross rods; theseamost' economically being of circular. section, formed of. steel, and of a'diam- -etersuch as ;to bridge and engage without dislocation the upper or lower courses. of the stressed wireielements, the wireelements of the upper :course beingindicated atz22 and those of the lower coursebeinguindicatedzat 23. l-Aconvenient size of the cross rods indicated at 24 is 4 inch, in the :example. shown this being the space between the rtwo courses ofxwires;22 andv 23, so that the wires make contact with :the :crossrods and tend to position them. In thewexample illustrated the rods'v are spaced: onacenters of v 4% andnotherdimensions given being-of course considered solely by way of example.

Assuming, as is preferredimpanels-for use in and as external wall elementsof buildings, that such panels will be formed of two or more :of the slabsi'20and 2 I; it, is desirable to provide suitable 'means. fora-assembling theslabs securely,v rigidly and: permanently 1'10 each;;other, :for: which purpose there are provided a plurality-of brackets,

.= consisting of steel-barsor; plate elements generally indicated at 25. These are located in the form inaccordance with a' pattern, fixed-as by atem- :plate; locating jig: or the.like,,so that the brackets :project fromxthe slab .in a predetermined, pref- ;erablysymmetricalpattern, such as will both fa- -cilitate:and assurematching of those brackets of {each slab withwcorresponding bracket elements .ofsanadjacentslab. The members-25 will-be ,formedof fiat striporplate, or of round stock as preferred; each: member as shown, being bent into ageneral-omega or u-shapezeachbracket presentingiin the completed;slab,1an-apex or rounded zbight- 26gtogether with divergent legs 21, .and -more.r sharply :divergent; terminal projections 28, the terminals (being 'flared outwardly into subinches, these 2.

4 stantial alignment and thus presenting a substantial area of anchorage within the slab.

As will appear from the drawing, the spacing of the cross rods 24 is such that they are engaged by the terminals of the Ushaped elements. This provides a firm and substantial relation between the ends of the metal brackets and the reinforcing structure within the slab. For fixation of location of the brackets 25 in the form or mold,

andtozsecure. the brackets-.to the rods, virtually integrally united thereto, fillet welds as shown at 3ll may be employed to assemble the bracket terminals 28 to the adjacent cros rod 24.

- Itshould be'noted that for many purposes, such as in internal partitions or the like, the individual 1 slabs such -as -20 and 2| may be employed each as ,a.single.thi ckness building panel of requisite strength with or without the rods 24, and in many casesiwithout the brackets 25, although it is preferred for outside usageto construct a double wall panel of a pair ofthe= slabs 2lland 2!. In the latter case theslabs arearranged in a pattern withthe corresponding brackets 25 in substantial registry as shown. It will have been noted as a preference to locate the brackets so that each thereof lies in a. longitudinal plane, in respect to the slab, and so that thebrackets. are disposed in pairs, somewhat inwardlyof opposite lateral marginsof the'slab and with their terminals spaced from the adjacent tension wires.

For assembly of the slabs in a common panel, a pair thereof are "disposed in a suitable holding device or jig, with the'bightsor apices 26 of the adjacent brackets securelywelded or otherwise firmly secured together while maintaining the slabs .20 and 2|, in accurate parallelism, the welding zones being identified with the fillet welds indicated at 31.. After welding and following any sealing and securment material at the joint. It

willhave appeared from a consideration of the structure of the two slab pane1,.that the two surface members, such as slabs 20 and 2|, in the combination with the elements 25, results in a truss structure of which the slabs constitute the inneror outer, or bottom and top chords, with the weldedbrackets collectivelyconstituting a web structure between the chords.

Referring ,now to a preferred method comprising the steps forming the slabs, and therefrom .the panel ,lunits, .there is indicatedas a preference to providean elongate :form or mold, preferably of a. length somewhatexceeding that of a plurality of the slabs. For example, in the case of a panelapproximating 9ft. in length, eachslab. havins-thmsamelength, the inside length of the form for pouring six nine-foot panels, is of. the orderiof 54 it, plus some addi- .tional form length to compensate for actual length shrinkage incident to the prestressing .techniquefhereinafter. described. Such reduction in slab length may amount to several inches in a formed of wood or other suitable material including a bottom, end closures 36 and removable cross partitions 31. Each of the elements 36 and 31 is preferably provided with a row of key-hole openings 40, so shaped to facilitate top insertion of the longitudinal tension wires, each such opening including a lowermost circular portion from which extends upwardly a slot to the top of the element, it being noted that the openings 40 are arranged in two depthwise staggered series corresponding to the location of the courses of the tension wires.

Located exteriorly of the mold or form and near one end thereof, is an anchor shaft or rod 4! to which the several tension wires 22 and 23 are secured. As may be desired, two of the rods 4| may be provided, one above another, each serving as an anchor element for one of the courses of wires 22 or 23. As will now be apparent, the parallel tension wires of the two courses are stranded along the top of the form and inserted in the several openings 40, which maintain the wire spacing depthwise in and laterally of the mold, and hence establish the predetermined positions of the wires in the finished slab or 2 I.

The tension wires having been thus passed through the mold or form from end to end thereof, are extended beyond the form end opposite the anchor shaft ll, and each wire is securely fastened to a small-diameter winding reel 42, a requisite member of which are carried in spaced relation on, and fixed to a rotatable tensioning shaft 43, provided with one or more worm gears 44. Shaft 43 is obviously subjected to a very low rate of rotation, in fact its actuation will usually consist of only a partial rotation. conveniently imparted by a worm or plurality thereof, each carried by the output shaft E5 of a reduction gear unit 46, the latter being powered by any suitable, preferably rotatable means such as a hand crank 41.

The specific proportions of cement, aggregate, sand and water, to constitute the concrete mix of which the slabs 20 and 2! are formed, may be within any of the conventional proportions of materials, and their nature and exact proportion selected according to usage and stresses to which the sla'bs or panels are to be subject in service. Assuming now the wires 22 and 23 to have been arranged in position in the mold, and tension imparted thereto through the actuation of shaft 43. This loading is substantial in degree, and by way of reciting present preference as to practice, but

without restriction, it may be of the order of 125,000 to 135,000 pounds p. s. i. cross section of each such wire. The prepared concrete mix is then poured to the requisite depth in the form or mold, and the latter subjected as may be desired and as preferred, to agitation, tamping action, or both, either of which is of itself conventional practice. Such consolidation may b accomplished by conventional means, and following which step the now poured slab is caused to set substantially completely, the extent or time of setting being determined by preliminary trials, but isin any case sufficient to create a definite, permanent bond between the wires and the mix. A strain gauge or the like may be employed at the time of tensioning so as accurately to control wire loading. Following release of tension of wires 22 and 23, the slab is permitted to age sufficiently to relieve it of any of its green character. Following this, the cross partitions or spacers 31 are removed, the slabs removed from the mold, and severance of the wires thereof eifected in any suitable manner, as by a rotary saw, or gang thereof. The individual slabs such as 20 and 2| may now be stored, stacked or transported to a suitable station for their ultimate use in this form, or for assembly into the multipleslab panels to be further described.

In further referenc to the steps involv d in casting the slabs, it will be understood as not necessary in all cases to include the cross rods 24, nor in all cases to utilize the brackets 25. However, if either or both of these elements are to be utilized, while the wires are yet under a low tension, the rods 24 may be inserted therebetween, and located preferably at a right angle thereto. It has been noted that the diameter of rods 24, if of round stock, is preferably such that the rods easily fill the vertical space between the inner and outer courses 22 and 23 of the wires, so as to avoid dislocation thereof. It is preferred, upon insertion of the web members or supports 25, to dispose each thereof in a vertical plane with its outturned terminals in a position to be embraced within the slab, and with each terminal metallically united, as by weld 30, to one of the rods 24.

It should be noted that for certain buildings or elements thereof, it may not be desirable to form a double slab withthe slabs thereof in parallelism. However, when employed as elements of the wall of the building or the like, it will usually be desirable to dispose the slabs such as 20 and 2| in a suitable holding device or jig (not shown) close to parallelism as possible. In the location of the brackets 25 in the form, it has been noted as a preference to arrange these in a symmetrical pattern, and with the several brackets disposed in rows projecting outwardly of the adjacent faces of the web members, and each extending at substantially a right angle from the slab face. Such an arrangement assures that when the slabs carrying the brackets are disposed in an assembly jig, the extremities of the brackets will engage, preferably abutting each other, in which zone of contact they are welded together, as indicated by the. fillet welds shown at 3|. Upon completion of welding, and any further finishing operations desired, the twoslab panel is now in condition for shipment and erection.

A variant in structure and practice of producing a single-slab panel is shown by Figs. 8 and 9, wherein the slab is generally indicated at 50. In this form wires 5! may constitute the 8015; internal metal reinforcement, and are tensioned in accordance with the steps described in forming slabs 20 and 2|, other steps of pouring, etc., being similar in the case of slab 56. This form of slab is desirably provided with cored passages or bores 52, extended transversely but fully within and through the slab, serving to receive tie elements such as metal rods or bolts (not shown) used in erection and assembly, for example in inside work such as partitions. The passages 52, With bolts or the like therethrough, enable assembly under conditions of edgewise compression.

A desirable variant for some purposes is a floor panel of a double character, generally indicated at 55, Fig. 7, in which a complete slab and bracket assembly 56, similar to 2025 as described, is secured, say in parallel relation as by welding at 51, to a metal plate 58. Although the twoslab panel is admirably adapted for use as floor ing sections, the panel or section 55 offers advantages for many other purposes. In this "structurey-the outer slab is the counterpart of slab 20, and theelement 58,-the counterpart of slab 2|.

'Certain added steps may sometimes be desirable, particularly when the panels are for use in residential buildings. One such example consists of the treatment of the outer face of the innermost slab of each panel to render it moistureproof and waterproof, for example by the addition of a layer or coating of a bitumastic material'BU. Further, it is sometimes desirable to form a seal between the adjacent panels following their erection in the wall or the like. For this purpose there is provided along the lateral margins of the front face of each of the adjacentpanels, such as '29, the rectangular undercut channel-indicated at'32', these mating in. adjacent panels for the reception of any suitable. sealing material or attachment compound BL. Such channels are easily formed'by insertion of filler strips (not shown) 'in the mold, andmay be similarly formed at top and bottom of thezoutside slab when desired.

L'It. will have been noted. that the open .end construction andthe spacing between the brackets of the two-slab panel, also in panel 55, providesfor the' 'ready introductionoffibrousor other insulation material as." may the .desired, andcthat by reason of the: relatively restricted areas 'of unionfof the twospaced slabs, these consisting of the: welding or securement comes, only aminimum path of: conductive heat: travel obtains" between theinner and outer slabs of the panel,'whereby the panel is inherently of a highly insulated-character.

Although therinvention-has been described by making :particularized references -to a preferred structure and method, the detail of description is to-be understood solely as instructivarather than in any limiting 2 sense; numerous ,variants being possible without departure from: the, full intended-scope of the claimshereunto appended.

. I claim as. my invention:

1. 'A panel for use in' multiple to "constitute the walls, roof :and like structure of abuildin .each said panel consistingof a pair of. relatively thin concrete slabsof rectangular shape, a plu- -rality of courses"of:steelwire of high tensile strength, the wires. of each'course being substantially parallel and spaced, and the-courses thereof beingidepthwise spaced withinthe slab, .a plurality ofcross rods of a; diameter to-bridge the space between the courses'of wire,'the wire within the slab being permanently longitudinally, stressed; a plurality of steelibracketseach of approximately U-shape and each :having' its ends embedded within the slab, the free endsof :the arms of. thebrackets diverging therefrom. so as to formzoutstanding terminal'portionsythe brackets beingdisposed with their terminal portions-within the slab and with the rodsadjacent said terminal portions whereby firmly to anchor the-brackets within the slab, tiemeansengag- .ing certain, of saidterminal portions and'the cross rods; a pair of said slabs forming the faces of each panel and beingv arranged in back-toback relation, the spacing therebetween approximately twice thesprojecting. dimension "of the individual brackets; the brackets being arranged in predetermined corresponding patterns-Brand on eachof the slabs, and the bight portions of theadjacent brackets being welded together to maintain the spacing and assembly of the slabs in the panel.

j 2. Aibuilding panel consisting of a pair of concrete slabs,z each of said slabs including aseries "of laterally and'depthwise spaced; substantiall :parallelelongate pre-tensioned elements within and bonded to the concrete matrix'of the slab gether to hold said slabs in spaced relationship.

3. A building panel consisting of a pair of concrete slabs, a series of laterally and depthwise spaced, elongate pre-tensioned elements within and bonded to the concrete matrix of the slab keeping the slab under permanent compression, rod elements extended across, and depthwise bridging certain of said pre-tensioned elements, a plurality of brackets projecting outwardly of the faces of said slabs, each of said brackets being secured to th rod elements and being of approximately U-shape to form a closed loop exteriorly of each slab, the bight portions of the loops of opposed brackets of said slabs being secured together to hold said slabs in spaced relationship.

1. A panel for use in multiple to constitute the walls, roof and like structure of a building, each said panel consisting of a pair of relatively thin concrete slabs of rectangular shape, a plurality of courses of steel wire ofhigh tensile strength, the wires of each course being substantially parallel and spaced, within the slab, a plurality of cross rods of a diameter tobridge the space between the courses of wire, the wire within the slab being permanently longitudinally.stressed, and being bonded to the concrete matrix of the slab keeping th slab under permanent compression; a plurality of steel brackets each of approximately U-shape and each having its ends embedded within the slab, the free ends of the arms of the brackets diverging therefrom so as to form outstanding terminal portions, theterminal portions of eachbracket being'disposed in mutual align ment, the brackets being disposed with their terminal "portions within the slab and adiacent successive cross rods, tiemeans securing the terminal portions of each bracket to successive cross rods, whereby to anchor firmly the brackets within the slab; a pair of said slabs forming the faces of each panel and being arranged in backto-back relation, the spacing therebetween being approximately twice the projecting dimension of the individual brackets; the brackets being arranged in predetermined corresponding patterns in and on each of the slabs, and the bight portions of the adjacent brackets being welded together to maintain the spacing and assembly of the slabs in the panel.

5..A building panel consisting of a concrete slab, a series of laterally and depthwise spaced, substantially parallel elongate pre-tensioned elements within and bonded to the concrete matrix of the slab keeping the slab under permanent compression, rod elements extended across, and depthwise bridging certain of said pre-tensioned elements, a plurality of bracket elements projecting normal to the face of and in predetermined pattern from the slab, saidbracket elements being secured to the bridging rod elements and forming closed loops exteriorly of the slab, and means spaced from and in opposed relation to said slab, said means being secured to the exterior loops of said bracket elements, whereby to hold the slab in spaced relation to said means.

6. A building panel consisting of a concrete slab, a series of laterally and depthwise spaced, substantially parallel elongate pre-tensioned elements within and bonded to the concrete matrix of the slab keeping the slab under permanent compression, rod elements extended across, and depthwise bridging certain of said pre-tensioned elements, a plurality of bracket elements projecting normal to the face of and in predetermined pattern from the slab, said bracket elements being secured to the bridging rod elements and forming closed loops exteriorly of the slab, and a metal plate spaced from and in opposed relation to said slab, said plate being secured to the exterior loops of said bracket elements, whereby to hold the slab in spaced relation to said plate.

NEAL J. CAMPBELL.

References Cited in the file of this patent Number 799,784 1,102,991 1,344,767 1,568,266 1,656,168 19 2,088,645 2,153,741 2,234,663 2,299,071

15 Number UNITED STATES PATENTS Name Date Fisher Sept. 19, 1905 McKennee July 7, 1914 Madison June 29, 1920 Carrillon Jan. 5, 1926 Bowles Jan. 17, 1928 Fling Aug. 3, i937 Cobi Apr. 11, 1939 Anderegg Mar. 11, 1941 Rogers et a1 Oct. 20, 1942 FOREIGN PATENTS Country Date Great Britain Feb. 13, 1919 Great Britain July 24, 1930 Great Britain June 23, 1944 

